The present invention relates to a support structure for an axle housing of a towing tractor which is supported integrally at the opposite ends thereof by a suspension having leaf springs.
Japanese Patent Application Publication H11-291731 discloses a support structure for an axle housing of a towing tractor. According to the publication, the axle housing connecting the opposite wheels of the towing tractor is bound to a leaf spring by a spring seat, two U-bolts, a lower spring seat and a U-bolt restraining member and also supported by the leaf spring.
The spring seat includes a seat contacting with the leaf spring, a pair of side walls facing each other and extending from the opposite sides of the seat and a pair of gutter-shaped flanges extending outward from the respective side walls in opposite directions. The axle housing is supported on the leaf spring through the spring seat by engaging curved portion of the U-bolts with the axle housing, inserting leg portions of the U-bolts through the holes of the lower spring seat and screwing nuts on the threaded ends of the leg portions of the U-bolts.
Specifically, the axle housing is connected to the spring seat by welding the outer peripheral surface of the axle housing to the inner surfaces of the flanges of the spring seat for preventing the axle housing from rotating on its axis. The welded portion that is subjected to various kinds of forces such as torque, reaction force, loads from the road and the like requires high weld strength. Since the welding should be performed carefully, the working efficiency in forming the support structure of the axle housing is deteriorated. Furthermore, when the axle housing or the spring seat is to be replaced with a new part, they have to be replaced as a unit because they are welded together and, therefore, the replacement work will become costly.
The present invention is directed to providing a support structure for an axle housing of a towing tractor in which the axle housing can be supported on a leaf spring without welding a spring seat to the axle housing so that the spring seat or the axle housing may be replaced independently.